The development of III-V semiconductor compounds have made possible the fabrication of a variety of devices useful in industrial applications. Typical devices are lasers, light emitting diodes, detectors of various kinds including light detectors, memories, etc. Proper exploitation of the properties of these III-V compounds requires processing procedures often unique to semiconducting compounds. Typically, these techniques are directed toward smaller sized, more precise location of various features on the semiconductor material, unique geometrical features useful only with compound semiconductors, etc.
A particular case in point is the production of various geometrical features on compound semiconductors. For example, it is often required to etch a straight-walled hole in a semiconductor compound. Such a feature is often difficult to make because of the isotropic nature of most etching processes. In addition, for many optical devices, damage-free etching is preferred so as to minimize undesirable damage to the active areas of the device.
In fabricating such devices, particularly optical devices, it would be highly advantageous to have an etching procedure which can be controlled as to etch rate, area to be etched and geometrical shape to be etched. It is also highly advantageous that such procedures produce damage-free features, particularly where the etching procedure involves material close to or part of the active area of the device. Such a procedure would be useful for making channels or holes in various optical devices such as optical detectors.
It is also useful to have the etching process depend on semiconductor properties. For example, it is often advantageous that only n-type and intrinsic material be etched and not p-type material.